The present invention relates to a control panel device installed in an electronic machine such as an electronic musical instrument for setting a numerical data which is inputted to control performance of the electronic musical instrument.
Recently, a multiple of control parameters are provided for controlling an advanced type of the electronic musical instrument having expanded performance functions. Such an electronic musical instrument is installed with a control panel device utilizing a graphic user interface (GUI) to facilitate selecting and setting of the control parameters. Specifically, the electronic musical instrument admits numerical parameters or numerical data applied to a tone generator and else so as to control a tone volume, an acoustic effect, an envelope waveform and so on. Generally, an absolute value of the numerical data does not have significant, meanings, but a relative variation of the numerical data is effective to control the performance. Usually, the setting of the numerical data is carried out by relative shifting from an old value to a desired new value, or by returning to a particular standard or default value.
However, the conventional control panel device of the electronic musical instrument regularly utilizes a digit input piece such as a ten-key, which is suitable for setting an absolute value of a selected numerical data, but is rather inconvenient for continuously or incrementally changing the numerical data as noted above. The control panel device may include other operating pieces such as a slider piece and a rotary piece, which can be used to carry out the relative changing of the numerical value. However, an operating range thereof is physically limited by the mechanical structure to thereby obviate extensive variation of the numerical data. Consequently, the conventional electronic musical instrument is provided with rather redundant operating pieces for covering various setting modes of different parameters. Thus, the setting operation is rather complicated, and the control panel device is not reduced in size. Further, the operating pieces are located remotely from a display panel which indicates the parameters to be set. The operator must shift his eyes between the operating piece and the display panel during the setting of the numerical value in troublesome manner.